Typically, a substrate processing apparatus may be classified into a single wafer type substrate processing apparatus in which a substrate processing process is performed on one substrate and a batch type substrate processing apparatus in which a substrate processing process is performed on a plurality of substrates at the same time. The single wafer type substrate processing apparatus has an advantage in that its structure is simple. However, the single wafer type substrate process apparatus may be deteriorated in productivity. Thus, the batch type substrate processing apparatus is popular because of mass production capability.
A batch type substrate processing apparatus may include a processing room for receiving and processing substrates stacked in multi-level in a horizontal direction, a process gas supply nozzle for supplying a process gas into the processing room, and an exhaust line for evacuating the processing room. A substrate processing process using such a batch type substrate processing apparatus may be performed as follows: first, a plurality of substrates are carried into the processing room; next, interior of the processing room is exhausted via exhaust line and a process gas is supplied into the processing room via a process gas supply nozzle; next, the process gas sprayed from the process gas supply nozzle is passed between substrates and is flowed into the exhaust line through an exhaust opening while a thin film is formed on the substrate.
However, in a conventional substrate processing apparatus, some of process gas may not pass the upper surface of the substrate but move along a circumference of the substrate to be absorbed into the exhaust line. That is, the process gas moving along the circumference of the substrate may not actually participate in the processing process and is absorbed into the exhaust line. Thus, the process gas may be wasted and efficiency of processing process on a substrate may be declined.